Residual strains in GaN grown on 6H-SiC

The triple crystal modification of Bond method was used for lattice constant measurements and for the study of residual strains in GaN layers grown on 6H-SiC (0001) substrates. GaN layers grown by MOCVD employing AlN and AlCaN buffer layers and GaN layers grown by HVPE without buffer layer were investigated. It was found that the residual strains in GaN were considerably reduced by use of the AlGaN buffer layer. The dependence of residual strains on thickness and composition of buffer layer could be explained by the different degree of relaxation mismatch stresses and change of thermal stresses in GaN layers, known on SiC with different buffer layers. (C) 1997 Elsevier Science S.A.